Valve gear



Sept. l10, 1929. y A, M NlXQN 1,727,782

VALVE GEAR Filed Nov.v 8, 1924 2 Sheets-sheet 1 a fi q. 1 b E-Lhz INVENTOR. 1MM/Wire BY f A TTORNE Patented Sept. 10,` `1929. J, l il ANDREW M. NIXON, OF LYNN, MASSACHUSETTS.

vALvE GEAR.

Application led November This invention relates to yvalve Operation for steam pumps and the like and particularly to direct acting pumps such as feed pumps, in which a steady and positive feed is desired. In pumps of this type it has been supposed necessary to operate by a piston valve, but such pistons being liable to rather rapid wear, soon become leaky and unreliable and cannot be readily repaired without shutting down.

My present invention contemplates an oscillating valve and valve gear by which I am able to get a very positive and reliable operation and which is of a construction so simple as to involve inexpensive installation and great ease in adjustment or repair.

As illustrative of my invention I have shown in the accompanying drawing and will discuss in the following specification 2O an embodiment which is specifically of great utility and which also well` illustrates the principles involved by which other modiiications and variants of myinvention may be designed by others skilled in the art.

Throughout the specification and drawings like reference numerals are employed to indicate corresponding parts, and in the drawings: n

Fig. 1 is a vertical section through said 0 valve and gear.

Fig. 2 is a face view thereof.

Fig. 3 is a somewhat diagrammatic view of parts of the valve and the gear, and

Fig. 4 is an elevation, partly in section, showing my valve gear applied to a feed pump o-f conventional type.

In considering my invention in the embodiment shown, the actuating means is the usual positive stroke control. I have shown at 1 a lever operated by a piston P to reciprocate a rod 2, with which it engages between the adjustable nuts 3.

. The rod 2 is pivoted at one end midway of the lever 4, which is hung at f1 in a bracket 5. The lever 4; carries an arm 6 formed of a pair of spaced members and having a rollerl 7 between the ends thereof. The valve case or steam chest 8 covers the two intake ports 9 and 10 of the pump cylinder C s, 1924;; serial No.` 748,553.

andfis'provided with an exhaust 11. The ports Quand 10 are preferably oppositely disposed and are controlled byl a Vpair "of valve members 12 on a' valve stem 13.

'Thevalve'members 12 are set so thatone 55,

will coverfits port, while the yother'is uncovered, these movements..y being j'effected by a slight partial rotation Aof the stem 13. f The. casing 8 is provided with an overhanging bridge or framebmember 8,1y in'O,y

which the `sternl 13 has ,bearingff It also affords 'a bearing Safor the'fend of the kconnecting link 1,5'whi`ch is attached tothe arm 6' and is iittedwith a spring 16.` yThe spring 16 is coiled about the link 15 and at 6a one end abutsk the ybearing 8LL and at its other endis provided with a' cap 16a which abuts a slightly rounded washer 1,61k helden the link 15 by ya nut 151. The function of this spring is' to yieldinglydraw the arm 6y 70 inwardly `towards the valve stem. ,The valve stem carries neary its upper end acam karm 17 against which the roller 7 bears. As therod 2 is reciprocated the roller 7 is adx-` vancedfrom the position shown in'Figure'2, 75

cam itis drawn in by the spring 16 so that 80 it lies over the cam inthe position indi-y cated kin `l*`igure`3 closin'gfthe lower port 10`and opening the upperport 9. Upon the] returnystroke of the rod 2, the arm 6 is f drawn downward, 'its continued motion caus- .85p ing the'roller 7 "to ridev back over the toe ofthel cam toits original position shown in v Fig. 2. The valve is' checked atits two positions by check pieces 18, which are cast or` attached on the' faceof the cylinder or other convenient place i kof mounting. With such gear the piston gets full steam from the beginning to the end of the stroke. p* There isrno dead centerto be'overcome and 95 the action is positive'whether the 'pump is working fast or slow.y Theoperation is as follows: ySteamy is admitted from an'ylsuitable steam source through `the steam `inlet 19 into the'steam chest8 and passes through k100` one or the other of the ports 9 and 10, depending` upon the osition of the valve 12, into the cylinder In Fig. 3 the port 9 is uncovered and the live steam would therefore Vpass through said port on top of the piston P and force the piston downwardly. When the piston reaches the extremelimit of its downward stroke, the lever 1 will be actuated, and through the connec-tionst, 6, 7 and 17 will reverse thepositionof the valve Y so as to cover port 9 and uncover port 1(7), permitting the steam in the pump cylinder to exhaust through port 9 and exhaust y,port 11, whereupon the live Asteam within 'the chest 8 will enter port 10 ,rand the actionwill be vrepeatedin the reverse direction. The live steam tends; to always tforce valvek 12,to its seat aso that the valve l2 always covers the yexhaust port'll andl preventsl the `live steaml within the steam chestjS `trom exhausting throughfsaid port, but the valveis a hollow valveso that the exhaust steam'from either port9 or portk 10 canpass through y. Athe valve intosaidv port.

- yThe embodiment showniis a simple and satisfactory forni andis especially suitable for marine purposes. Various mo-diications may, however, be made inthedesign of lthe ,f valve and thef,gear, all `without departing from the Vspirit Vof ymy invention: if within the limits Yof the appended claim.

"WhatI therefore claim and, desire tose-y cure by Letters yPatent is: l v

In valve gear for usewith aA cylinderhaving a pair of spacedv oppositely 'disposed f intake ports and an exhaust port, and a pis ton reciprocating in said cylinder, avalvle casing'having an inlet for a fluid undery presf v sure, a hollow valve mounted for oscillation y,.iiuid may pass into thecylinder vthrough the vuncovered portA and move theL piston in one direction within thecylinder, andmotion Y 'in said casing and const-antlyseated over said exhaust port by the pressure ofthe vfluid admitted into said casing, said valve v Vhaving a` pair vrof'intake port-blocking faces vadapted alternately ,to cover fand vuncover isaid intake ports yand so disposed as to each other and as toY said intake ports `thatfwhen one of said intakeports isblocked the other will :be uncovered, whereby the (pressure,

transmitting connections between said pisto-n and-valve comprising a cam `armkgronthe .valve stem, a reciprocatingarm disposed for movement inl thepath of y"the .cam arm, a level-"for reciprocating said arm,arresilient link for yieldin-gly holding ysai'dyreciprocating arm 'in engaging alinement with said cam arm, Yand an operating connection ,from

the piston toy said leverweifective when-the piston reaches Aits limit of travell in :said .di-

rection ,to reverse the `positionvof the valve .whereby the pressure fluid-within the cylinder may exhaust through the now uncovered lll) 

